This invention relates to a calorimeter detector that can be used in conjunction with high energy physics particle collider experiments. In particular, this invention is a method for and a system of achieving improved resolution from a depleted uranium calorimeter detector by inferring the hadron content of the calorimeter excitation.
One of the fundamental experiments in high energy physics is to cause particles to collide into targets (or other particles) and observe the results of these collisions. Physicists have tried over the years to increase the energy of these collisions in order to produce heretofore undetected subatomic particles (or learn more about known particles) in order to advance the theoretical understanding of matter and energy. The collider at Fermilab is an example of a device used to conduct this type of experiment. New colliders have been proposed, such as the Superconducting Super Collider in Texas and HERA in West Germany, that would impart even more energy to the colliding particles.
A high energy physics collider includes an accelerator portion and a detector portion. The accelerator portion gets the particles moving in specific paths at very high energies and causes the particles to collide with other particles. The detector portion of the collider provides the experimenters with information about the results of the collisions, in particular the trajectories and energies of the resultant particles. Both the accelerator portion and the detector portion define the limits of the collider's utility. Accordingly, the accelerator and the detector are designed to complement each other. Advances in accelerator design to impart more energy to the colliding particles must coincide with improvements in detector design to record the products produced by the collisions. It follows that accelerating particles to a new, higher level of energy would have little utility if the detector equipment associated with the collider could not measure or observe the results of collisions that occurred at that energy. Moreover, since the costs of detector design are part of the overall budget for construction of a collider, an improvement in resolution of the detector can result in significant savings for the project or make available funding for other aspects of the collider that would otherwise have to be spent on the detector.
Different types of detectors are used at modern high energy physics colliding beam facilities. The detectors are constructed so that they surround the interaction region, i.e. the area where the collisions take place. The detectors consist of layers of electronic equipment which are sensitive to different properties of the particles which traverse them. The innermost layers or regions are usually devoted to a type of detector which is a tracking device that provides information about the position of the particles as they leave the interaction region. The next layer or region usually includes a type of detector which is a calorimeter that measures the energy of the particles leaving the interaction region. Usually in the outermost layer or region, there is included a type of detector devoted to detecting and identifying muons. Information from all these layers of detecting equipment is transferred to a host computer when an event of interest has occurred in the interaction region.
When high energy particles enter the calorimeter detector, they interact with the massive material of the calorimeter and the result is a shower. The particles which cause the shower are both hadrons and leptons in some proportion to one another. The function of the calorimeter detector is to measure the energy of the incident particles, and the resolution with which the measurement is made is of critical importance in a physics experiment. Typically, in a calorimeter in a high energy physics detector, one of the factors limiting the resolution is that the response of the calorimeter to a hadron and a lepton is different. A very considerable amount of effort is given to trying to make the e/h ratio equal to 1, i.e. to make the response of the calorimeter the same for leptons and hadrons of the same energy.
One method of making the calorimeter response independent of particle type is to use depleted uranium for the dense medium of the calorimeter detector. If depleted uranium is used in the calorimeter detector, a fission mechanism can, under the right circumstances, compensate the calorimeter response, such that the e/h ratio is adjusted closer to unity thereby making the calorimeter detector less energy dependent.
Accordingly, it is an object of the present invention to provide improved resolution from a calorimeter detector used for high energy physics experiments.
It is another object of this invention to provide improved resolution from a compensated calorimeter detector in a efficient manner and without the inclusion of complex and expensive equipment.
It is another object of this invention to provide a system and method for improved resolution in a depleted uranium calorimeter detector.
It is still another object of this invention to provide a system and method for an improved resolution in a depleted uranium calorimeter detector through differentiation of the response of the calorimeter detector to leptons and hadrons.
It is yet another object of the present invention to provide a means to infer the hadron content of the response of a calorimeter detector to provide improved resolution in an off-line analysis.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.